This application is a divisional of U.S. application Ser. No. 12/458,341, filed Jul. 8, 2009, now U.S. Pat. No. 8,071,246, which is a continuation of U.S. application Ser. No. 10/866,238, filed Jun. 14, 2004, now U.S. Pat. No. 7,575,822, which is a continuation-in-part of U.S. application Ser. No. 10/446,704 filed on May 29, 2003, now U.S. Pat. No. 7,482,078, which claims benefit of priority of U.S. Provisional Application Ser. No. 60/461,190 filed on Apr. 9, 2003, all of which are incorporated by reference in their entirety. U.S. application Ser. No. 10/866,238 is also a continuation-in-part of U.S. application Ser. No. 10/653,240 filed on Sep. 3, 2003 now U.S. Pat. No. 7,364,810, which is incorporated by reference in its entirety.
The present invention is generally directed to fuel cells and more specifically to fuel cell operation.
Fuel cells are electrochemical devices which can convert energy stored in fuels to electrical energy with high efficiencies. There are classes of fuel cells that also allow reversed operation, such that oxidized fuel can be reduced back to unoxidized fuel using electrical energy as an input. The ability to generate electricity and regenerate fuel makes these fuel cells suitable for electrical energy storage. The fuel cells are usually operated at a predetermined optimum operating efficiency and/or throughput. The optimum operating efficiency is calculated for each fuel cell based on various fuel cell structural and operating parameters, such as fuel cell size, materials, fuel used, fuel flow rate, etc.